THE GEOGRAPHY OF SPAIN

Spanish territory comprises nearly five-sixths of the Iberian Peninsula, which the nation shares with Portugal, the micro-state of Andorra, and the British possession of Gibraltar. Spanish territory also includes two sets of islands--the Balearic Islands (Spanish, Islas Baleares) in the Mediterranean Sea and the Canary Islands (Spanish, Canarias) in the Atlantic Ocean--and two city enclaves in North Africa, Ceuta and Melilla. Peninsular Spain, covering an area of 492,503 square kilometers, consists of a central plateau known as the Meseta Central, which is enclosed by high mountains on its north, south, east, and part of its western sides. The area that is predominantly plateau also encompasses several mountain systems that are lower than the peripheral mountains. Although Spain thus has physical characteristics that make it, to some extent, a natural geographic unit, there are also internal geographic features that tend to compartmentalize the country.

The topographical characteristics also generate a variety of climatic regimes throughout the country. By far the greatest part of the country, however, experiences a continental climate of hot, dry summers and rather harsh, cold winters. Where these conditions prevail, the soils have eroded, vegetation is sparse, and agriculture is difficult. Irrigation is practiced where possible, but it is difficult because the flow in most streams is seasonally irregular, and the stream beds of larger rivers are frequently much lower than the adjacent terrain.

External Boundaries and Landform Regions
Most of Spain's boundary is water: the Mediterranean Sea on the south and east from Gibraltar to the French border; and the Atlantic Ocean on the northwest and southwest--in the south as the Golfo de Cadiz and in the north as the Bay of Biscay. Spain also shares land boundaries with France and Andorra along the Pyrenees in the northeast, with Portugal on the west, and with the small British possession of Gibraltar at the southern tip. Although the affiliation of Gibraltar continued to be a contentious issue between Spain and Britain in the late 1980s, there were no other disputes over land boundaries, and no other country claimed the insular provinces of the Balearic Islands and the Canary Islands.

The majority of Spain's peninsular landmass consists of the Meseta Central, a highland plateau rimmed and dissected by mountain ranges. Other landforms include narrow coastal plains and some lowland river valleys, the most prominent of which is the Andalusian Plain in the southwest. The country can be divided into ten natural regions or subregions: the dominant Meseta Central, the Cordillera Cantabrica and the northwest region, the Iberico region, the Pyrenees, the Penibetico region in the southeast, the Andalusian Plain, the Ebro Basin, the coastal plains, the Balearic Islands, and the Canary Islands. These are commonly grouped into four types: the Meseta Central and associated mountains, other mountainous regions, lowland regions, and islands.

The Meseta Central and Associated Mountains
The Meseta Central, a vast plateau in the heart of peninsular Spain, has elevations that range from 610 to 760 meters. Rimmed by mountains, the Meseta Central slopes gently to the west and to the series of rivers that form some of the border with Portugal. The Sistema Central, described as the "dorsal spine" of the Meseta Central, divides the Meseta into northern and southern subregions, the former higher in elevation and smaller in area than the latter. The Sistema Central rims the capital city of Madrid with peaks that rise to 2,400 meters north of the city and to lower elevations south of it. West of Madrid, the Sistema Central shows its highest peak of almost 2,600 meters. The mountains of the Sistema Central, which continue westward into Portugal, display some glacial features; the highest of the peaks are snow-capped for most of the year. Despite their height, however, the mountain system does not create a major barrier between the northern and the southern portions of the Meseta Central because several passes permit road and railroad transportation to the northwest and the northeast.

The southern portion of the Meseta is further divided by twin mountain ranges, the Montes de Toledo running to the east and the Sierra de Guadalupe, to the west. Their peaks do not rise much higher than 1,500 meters. With many easy passes, including those that connect the Meseta with the Andalusian Plain, the Montes de Toledo and the Sierra de Guadalupe do not present an obstacle to transportation and communication. The two mountain ranges are separated from the Sistema Central to the north by the Tagus River.

The mountain regions that rim the Meseta Central and are associated with it are the Sierra Morena, the Cordillera Cantabrica, and the Sistema Iberico. Forming the southern edge of the Meseta Central, the Sierra Morena merges in the east with the southern extension of the Sistema Iberico and reaches westward along the northern edge of the Rio Guadalquivir valley to join the mountains in southern Portugal. The massif of the Sierra Morena extends northward to the Rio Guadiana, which separates it from the Sistema Central. Despite their relatively low elevations, seldom surpassing 1,300 meters, the mountains of the Sierra Morena are rugged.

The Cordillera Cantabrica, a limestone formation, runs parallel to, and close to, the northern coast near the Bay of Biscay. Its highest points are the Picos de Europa, surpassing 2,500 meters. The Cordillera Cantabrica extends 182 kilometers and abruptly drops 1,500 meters some 30 kilometers from the coast. To the west lie the hills of the northwest region.

The Sistema Iberico extends from the Cordillera Cantabrica southeastward and, close to the Mediterranean, spreads out from the Rio Ebro to the Rio Jucar. The barren, rugged slopes of this mountain range cover an area of close to 21,000 square kilometers. The mountains exceed 2,000 meters in their northern region and reach a maximum height of over 2,300 meters east of the headwaters of the Rio Duero. The extremely steep mountain slopes in this range are often cut by deep, narrow gorges.

Other Mountainous Regions
External to the Meseta Central lie the Pyrenees in the northeast and the Sistema Penibetico in the southeast. The Pyrenees, extending from the eastern edge of the Cordillera Cantabrica to the Mediterranean Sea, form a solid barrier and a natural border between Spain and both France and Andorra that, throughout history, has effectively isolated the countries from each other. Passage is easy in the relatively low terrain at the eastern and western extremes of the mountain range; it is here that international railroads and roadways cross the border. In the central section of the Pyrenees, however, passage is difficult. In several places, peaks rise above 3,000 meters; the highest, Pico de Aneto, surpasses 3,400 meters.

The Sistema Penibetico extends northeast from the southern tip of Spain, running parallel to the coast until it merges with the southern extension of the Sistema Iberico near the Rio Jucar and with the eastern extension of the Sierra Morena. The Sierra Nevada, part of the Sistema Penibetico south of Granada, includes the highest mountain on the peninsula, Mulhacen, which rises to 3,430 meters. Other peaks in the range also surpass 3,000 meters.

Lowland Regions
The major lowland regions are the Andalusian Plain in the southwest, the Ebro Basin in the northeast, and the coastal plains. The Andalusian Plain is essentially a wide river valley through which the Rio Guadalquivir flows. The river broadens out along its course, reaching its widest point at the Golfo de Cadiz. The Andalusian Plain is bounded on the north by the Sierra Morena and on the south by the Sistema Penibetico; it narrows to an apex in the east where these two mountain chains meet. The Ebro Basin is formed by the Rio Ebro valley, contained by mountains on three sides--the Sistema Iberico to the south and west, the Pyrenees to the north and east, and their coastal extensions paralleling the shore to the east. Minor low-lying river valleys close to the Portuguese border are located on the Tagus and the Rio Guadiana.

The coastal plains regions are narrow strips between the coastal mountains and the seas. They are broadest along the Golfo de Cadiz, where the coastal plain adjoins the Andalusian Plain, and along the southern and central eastern coasts. The narrowest coastal plain runs along the Bay of Biscay, where the Cordillera Cantabrica ends close to shore.

The Islands
The remaining regions of Spain are the Balearic and the Canary Islands, the former located in the Mediterranean Sea and the latter in the Atlantic Ocean. The Balearic Islands, encompassing a total area of 5,000 square kilometers, lie 80 kilometers off Spain's central eastern coast. The mountains that rise up above the Mediterranean Sea to form these islands are an extension of the Sistema Penibetico. The archipelago's highest points, which reach 1,400 meters, are in northwestern Majorca, close to the coast. The central portion of Majorca is a plain, bounded on the east and the southeast by broken hills.

The Canary Islands, ninety kilometers off the west coast of Africa, are of volcanic origin. The large central islands, Gran Canaria and Tenerife, have the highest peaks; on Gran Canaria they rise to 1,950 meters and on Tenerife, to 3,700 meters.

Climate
Peninsular Spain experiences three climatic types: continental, maritime, and Mediterranean. The locally generated continental climate covers the majority of peninsular Spain, influencing the Meseta Central, the adjoining mountains to the east and the south, and the Ebro Basin. A continental climate is characterized by wide diurnal and seasonal variations in temperature and by low, irregular rainfall with high rates of evaporation that leave the land arid. Annual rainfall generally is thirty to sixty-four centimeters; most of the Meseta region receives about fifty centimeters. The northern Meseta, the Sistema Central, and the Ebro Basin have two rainy seasons, one in spring (April-June) and the other in autumn (OctoberNovember ), with late spring being the wettest time of the year. In the southern Meseta, also, the wet seasons are spring and autumn, but the spring one is earlier (March), and autumn is the wetter season. Even during the wet seasons, rain is irregular and unreliable. Continental winters are cold, with strong winds and high humidity, despite the low precipitation. Except for mountain areas, the northern foothills of the Sistema Iberico are the coldest area, and frost is common. Summers are warm and cloudless, producing average daytime temperatures that reach 21° C in the northern Meseta and 24 to 27° C in the southern Meseta; nighttime temperatures range from 7 to 10 C. The Ebro Basin, at a lower altitude, is extremely hot during the summer, and temperatures can exceed 43 C. Summer humidities are low in the Meseta Central and in the Ebro Basin, except right along the shores of in the Rio Ebro where humidity is high.

A maritime climate prevails in the northern part of the country, from the Pyrenees to the northwest region, characterized by relatively mild winters, warm but not hot summers, and generally abundant rainfall spread out over the year. Temperatures vary only slightly, both on a diurnal and a seasonal basis. The moderating effects of the sea, however, abate in the inland areas, where temperatures are 9 to 18 C more extreme than temperatures on the coast. Distance from the Atlantic Ocean also affects precipitation, and there is less rainfall in the east than in the west. Autumn (October through December) is the wettest season, while July is the driest month. The high humidity and the prevailing off-shore winds make fog and mist common along the northwest coast; this phenomenon is less frequent a short distance inland, however, because the mountains form a barrier keeping out the sea moisture.

The Mediterranean climatic region extends from the Andalusian Plain along the southern and eastern coasts up to the Pyrenees, on the seaward side of the mountain ranges that parallel the coast. Total rainfall in this region is lower than in the rest of Spain, and it is concentrated in the late autumn-winter period.

Generally, rainfall is slight, often insufficient, irregular, and unreliable. Temperatures in the Mediterranean region usually are higher in both summer and winter, and diurnal temperature changes are more limited than those of the continental region. Temperatures in January normally average 10 to 13 C in most of the Mediterranean region, and they are 9 C colder in the northeastern coastal area near Barcelona. In winter, temperatures inland in the Andalusian Plain are slightly lower than those on the coasts.

Temperatures in July and August average 22 to 27 C on the coast and 29 to 31 C farther inland, with low humidity. The Mediterranean region is marked by Leveche winds--hot, dry, easterly or southeasterly air currents that originate over North Africa. These winds, which sometimes carry fine dust, are most common in spring. A cooler easterly wind, the Levante, funnels between the Sistema Penibetico and the Atlas Mountains of North Africa.

Drainage
Of the roughly 1,800 rivers and streams in Spain, only the Tagus is more than 960 kilometers long; all but 90 extend less than 96 kilometers. These shorter rivers carry small volumes of water on an irregular basis, and they have seasonally dry river beds; however, when they do flow, they often are swift and torrential. Most major rivers rise in the mountains rimming or dissecting the Meseta Central and flow westward across the plateau through Portugal to empty into the Atlantic Ocean. One significant exception is the Rio Ebro, which flows eastward to the Mediterranean. Rivers in the extreme northwest and in the narrow northern coastal plain drain directly into the Atlantic Ocean. The northwestern coastline is also truncated by rias, waterbodies similar to fjords.

The major rivers flowing westward through the Meseta Central include the Rio Duero, the Tagus, the Rio Guadiana, and the Rio Guadalquivir. The Rio Guadalquivir is one of the most significant rivers in Spain because it irrigates a fertile valley, thus creating a rich agricultural area, and because it is navigable inland, making Seville the only inland river port for ocean-going traffic in Spain. The major river in the northwest region is the Rio Mino.